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West Nile Virus Activity --- United States, September 1--7, 2004

During September 1--7, a total of 138 cases of human West Nile virus (WNV) illness were reported from 22
states (Alabama, Arizona, Colorado, Georgia, Illinois, Kentucky, Maryland, Michigan, Mississippi, Missouri, Nebraska,
New Mexico, North Carolina, Ohio, Pennsylvania, South Carolina, South Dakota, Texas, Utah, Virginia, Wisconsin, and Wyoming).

During 2004, a total of 37 states have reported 1,191 cases of human WNV illness to CDC through ArboNET
(Table, Figure). Of these, 330 (28%) cases were reported from Arizona, 326 (27%) cases were reported from California, and 195 (16%) cases were reported from Colorado. A total of 663 (57%) of the 1,163 cases for which all data were available
occurred in males; the median age of patients was 51 years (range: 1 month--99 years). Illness onset ranged from April 23 to August 29; a total of 30 cases were fatal.

A total of 98 presumptive West Nile viremic blood donors (PVDs) have been reported to ArboNET in 2004. Of these,
37 (38%) were reported from Arizona, 20 from California, 10 from Texas, nine from New Mexico, four each from Colorado and Georgia, three each from Florida and South
Dakota, two each from Missouri and Wisconsin, and one each from
Iowa, Louisiana, Minnesota, and Oklahoma. Of the 98 PVDs, five persons aged 35, 50, 66, 69, and 77 years subsequently had neuroinvasive illness, and 24 persons (median age: 55 years; range: 17--75 years) subsequently had West Nile fever.

In addition, during 2004, a total of 3,574 dead corvids and 749 other dead birds with WNV infection have been reported from 44 states. WNV infections have been reported in horses from 32 states (Alabama, Arizona, Arkansas,
California, Colorado, Florida, Georgia, Idaho, Illinois, Iowa, Kansas, Kentucky, Michigan, Minnesota, Mississippi, Missouri, Montana, Nevada, New Jersey, New Mexico, North Carolina, Ohio, Oklahoma, Oregon, South Dakota, Tennessee, Texas,
Utah, Virginia, Wisconsin, West Virginia, and Wyoming) and in five dogs from Nevada and New Mexico. Three squirrels with WNV infection were reported from Arizona. Three unidentified animal species with WNV infection were reported from Illinois, Iowa, and Nevada. WNV seroconversions have been reported in 640 sentinel chicken flocks from 13 states (Alabama, Arizona, Arkansas, California, Delaware, Florida, Iowa, Louisiana, Nebraska, Nevada, Pennsylvania, South Dakota, and Utah) and in four wild hatchling birds from
Missouri and Ohio. Three seropositive sentinel horses were reported from Puerto
Rico. A total of 4,657 WNV-positive mosquito pools have been reported from 32 states.

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